Certain types of conventional ophthalmic surgery require breaking up lenticular tissue and solid intraocular objects, such as the intraocular lens into pieces so that it can be extracted from the eye. For example, extraction of lenses for cataract surgery is one of the most common outpatient surgical fields with more than 3 million cases performed annually in the United States alone. During cataract surgery a commonly used method for lens extraction is phacoemulsification, which incorporates using ultrasonic energy to break up the lens and then aspiration to remove the lens fragments through the instrument. Other methods of lens fragmentation and extraction may include the use of instruments such as hooks, knives, or laser to break up the lens into fragments and then extract through an incision in the cornea in an ab interno approach. Intraocular, ab interno fragmentation of the lenticular tissue is extremely important in cataract surgery in order to allow removal of cataracts from ocular incisions that are typically not exceeding 2.8-3.0 mm.
A disadvantage of some lens extraction techniques are unwanted complications from aspiration of the lens particularly with the use of phacoemulsification. Ultrasonic energy and high volume during phacoemulsification may create turbulent flow that may have a deleterious effect on the tissue within the eye such as the corneal endothelium.
Additionally, certain aspiration and inspiration configurations require large pieces of capital equipment as in the case of phacoemulsification or may require certain resources such as wall vacuum that may not be available in all surgical settings, particularly in underdeveloped areas. Convention aspiration devices may be an independent tube or cannula or may be associated with another device such as a phacoemulsification unit (“phaco system”). Flow control and pressure control of phaco systems typically requires electronic control by a main console. A hand piece is used that has a suction line extending from the hand piece to the main console. The hand piece also typically has an inspiration line with inspiration driven by simple gravity feed or by flow controlled by the main console with a fluid bag/cartridge mounted to the console.
Another problem with phaco devices and other devices using a remote vacuum source is that the suction lines are long that means that they will often contain compressible material during the procedure, such as gas or compressible tissue. Long suction lines of compressible material affects the responsiveness of suction at the tip when suction is turned on and off. The problem of responsiveness is exacerbated by manually deformable/compliant hoses and lines that also respond to changes in pressure when starting and stopping suction, which further delays initiation and termination of suction at the tip. Yet another problem with some systems is that the disposal enclosure is also exposed to vacuum pressure and, as such, the container and gas or other compressible material therein, also responds to changes in pressure and further contributing to the delay in initiation and termination of suction at the tip and contributing to the low responsiveness of some systems.
Still another problem with conventional methods and devices for aspirating material from the eye is that the suction opening can readily clog during the procedure. Suction must be stopped and, if necessary, the material removed independently with another instrument inside the eye. The necessity to stop the procedure and unclog the distal opening undesirably increases the procedure time and need for unnecessary manipulations of the instrument(s) in the eye.
A final problem with some devices is the cost and complexity of the systems. A lower cost alternative with the same or better performance would also be desirable alternative such as one not requiring a costly control console and electronic control system.